Leadbeater’s Possum Gymnobelideus leadbeateri population genetic data

Leadbeater's possum (Gymnobelideus leadbeateri) is a small, cryptic arboreal marsupial patchily distributed across the Central Highlands of Victoria, Australia. Ongoing declines since the species’ rediscovery in 1961 have led to its current listing as Critically Endangered under the Environment Protection and Biodiversity Conservation Act 1999. Population viability analyses (PVA) conducted in the 1990s modelled ongoing large-scale population declines as a result of timber management prescriptions. The mechanism for declines was the loss of large hollow-bearing trees and failure to maintain mature trees and recruit younger trees, and was predicted to result in the loss of up to 90% of Leadbeater's possums by the 2040s. This postgraduate study used a panel of 15-20 highly resolving microsatellite markers and mitochondrial D-loop sequence data, to infer historical gene flow and investigate current population structure. Patterns in the genetic data revealed (1) high levels of admixture among sampled central highlands populations; (2) that the isolated population of Yellingbo was highly genetically differentiated and had significantly reduced genetic diversity in comparison to other extant sampled populations; (3) the Yellingbo population may once have formed part of a larger genetic unit that is now extinct; (4) new information on dispersal and mating systems; and (5) past (pre-European) declines in population size. The findings of this study suggest that in addition to declines detected in the field and in line with predictions from PVA, future declines are highly probable, potentially to the point of extinction of this species.